Principal, Interest, Taxes and Insurance are the basic components of a typical monthly mortgage payment. Some properties may also have a common/maintenance charge (condos and co-ops), and some homes have a homeowner’s association fee (HOA). Some loan programs will also require Mortgage Insurance (MI) or Private Mortgage Insurance (PMI). Beyond your regular payment, it is wise to budget for maintenance expenses. The cost of upkeep will vary with the age, type, size, structure and materials used.